September 22, 1897.] 



Garden and Forest. 



37 1 



a host of herbaceous species, rooted on the decaying 

 remains of old tree stumps, or even on the accumulated 

 debris of many generations of Polygonum. At the level of 

 the flood water, marking the point where their drifting 

 seeds lodged, but in summer some inches above the water 

 line, are tangles of Bidens, Cyperus, and other herbs, 

 firmly anchored and vigorously growing in the crevices of 

 the bark of living trees, which still higher are covered with 

 foliaceous Liverworts, Mosses, Colleniaceous Lichens, 

 and not infrequently, great masses of Polypodium incanum. 

 Where the water is shallower occur the Swamp Maple 

 (Acer rubrum, Drummondii), Planera, the Swamp White Ash 

 (Fraxinus profunda), Catalpa, and Water Locust (Gledits- 

 chia aquatica), which, on the gradual intrusion of the low 

 shores or islands, give place to the usual swamp timber, 

 festooned with Supple-Jack (Berchemia), Cross-vine (Bigno- 

 nia capreolata), Trumpet Creeper (Tecoma radicans), 

 and Grapes. And the beautiful pink clusters of Mikania, 

 and the blue foliage of Cissus stans stand out in rich 

 contrast with the prevalent green. After a first day of this 

 unwonted experience one emerges into the usual noise and 

 bustle with the feeling that he has visited another world 

 quite different from anything he has ever seen, and 

 scarcely knowing which to admire most — the great soli- 

 tude of the place or the beautiful way in which Nature's 

 hand has adapted her children to a most unusual home. 



Missouri Botanic Garden. Win. TrehdSe. 



Sun-scald and Means for its Prevention. 



SUN-SCALD, as the term is commonly used in the 

 north-west, is the partial or complete destruction of 

 the bark of trees on the part of the trunk or main branches 

 facing the south-west, due, apparently, to exposure to the 

 sun's rays. It is a question whether this damage occurs 

 during the growing season or during winter or early spring. 

 The term is more commonly used with reference to fruit- 

 trees. 



My own observation leads me to the opinion that the 

 damage known as sun-scald may occur either during early 

 spring or during summer, under certain conditions, but that 

 the causes of the trouble differ at the two periods. In early 

 spring it probably results from alternate freezing and thaw- 

 ing of the bark, especially when unseasonably warm 

 weather, that excites the cambium cells to activity, is fol- 

 lowed by freezing weather. At this season it is most 

 common on young trees on which the bark has not yet 

 become rough and the living bark has not been inclosed 

 by dead cork layers. Often the trouble does not reach to 

 the cambium, and hence does not immediately injure the 

 tree further than to destroy the outer bark layers on the 

 exposed part. In severe cases the bark of older trees may 

 be entirely destroyed on the south-west exposure, so that 

 it loosens from the wood and finally cracks open, exposing 

 the wood to the attacks of injurious insects and fungi. 



Sun-scald often occurs during summer on trees that have 

 been recently transplanted or over-pruned, and sometimes 

 during protracted drought on trees of certain species that 

 have not been interfered with. In all these cases the cause 

 is probably the same, namely, the transpiration current, 

 which conveys the water from the soil to the leaves, is so 

 much checked that the bark of the trunk becomes over- 

 heated, causing death of the cambium. The Soft Maple, 

 Acer saccarinum, when properly treated, is entirely 

 hardy at Madison, Wisconsin, but I have seen trunks 

 of this tree several inches in diameter, the tops hav- 

 ing been too severely cut back, with a patch of dead 

 bark some inches wide, and extending from the ground 

 to the lower branches on the part of the trunk fac- 

 ing the south-west. Trees of the Sugar Maple and 

 White Birch, taken from the nursery and planted where 

 their trunks are fully exposed to the sun's rays, are often 

 destroyed by sun-scald the first or second season unless 

 their trunks are shaded. The trouble is not immediately 

 apparent, and is frequently not discovered until too late, 



for the foliage of the tree remains fresh. But examination 

 of the bark facing the south-west a short distance above 

 the ground reveals the fact that it is lifeless and that borers 

 have gained entrance beneath it. The latter not only work 

 beneath the injured bark, but eat into the cambium of the 

 live part, thus often completely girdling the tree. 



Fortunately, the preventive of sun-scald is very simple, 

 and surrounding the bark with non-conducting material. 

 or shading it in the exposed part, is all that is necessary. 

 Several devices are in use for this purpose. A thin board 

 is sometimes tacked to the trunk so as to face the south- 

 west, or two boards nailed together in the form of an 

 eaves-trough are sometimes tied to the trunk. A single 

 narrow board sharpened like a stake and driven into the 

 ground close to the trunk facing the south-west answers 

 the purpose fairly well. A hay rope wound about the 

 trunk from the ground to the lower branches is often used. 

 A screen, made by weaving common house lath together 

 with wire, has been much used in Wisconsin. This device 

 is rather heavy for slender trees, and if put on so as to 

 reach from the ground to the lower branches it sometimes 

 heaves up in winter, and so does harm. Rye-straw set 

 upright about the trunk and tied on with wool twine makes 

 a protection that costs but one cent for each tree, and is 

 readily applied to a crooked trunk and to the lower 

 branches. Experience shows that this will last five years, 

 which is usually as long as protection is needed. The 

 codling moth and other injurious insects do not appear to 

 harbor beneath this protection, as might be supposed. It 

 has recently been proposed to cheapen this protector by 

 sowing a few kernels of rye or oats about the trunk of the 

 tree immediately after planting, a method that has not yet 

 been tested to my knowledge. 



Experiment Station, University of Wisconsin. 



E. S. Gotf. 



Foreign Correspondence. 



London Letter. 



Lily Disease. — Cultivators of Liliums have for some years 

 been bothered by a disease which attacked the bulbs when 

 dormant. This was not easily detected, especially in im- 

 ported bulbs, but soon made its presence evident when the 

 bulbs were planted in moist soil. Its ravages among Japa- 

 nese Lilies have lately been most alarming, and I believe 

 it has also got into the Lily-fields of Bermuda. Mr. Massee, 

 of Kew, has investigated some diseased bulbs of L. specio- 

 sum and L. auratum, and the results are published in a 

 recently issued number of the Keiv Bulletin. The disease 

 is first revealed by the discoloration and softening of the 

 base of the bulb-scales, and this increases until finally the 

 whole bulb becomes pulpy and brown. This is caused by 

 a fungus which is described by Mr. Massee as a new spe- 

 cies, namely, Rhizopus necans, and figures of it accompany 

 his paper in the Kew Bulletin. lie found that the fungus 

 could not penetrate the unbroken tissues of the bulb-scales, 

 but gained an entrance through wounds and especially 

 through broken roots. He recommends a short immer- 

 sion in a one per cent, solution of corrosive sublimate or of 

 salicylic acid for diseased bulbs, neither of these substances 

 having any injurious effect on them if not immersed longer 

 than fifteen minutes. In addition to Lily-bulbs it readily 

 attacks and destroys the bulbs of Narcissi. Mr. Massee 

 recommends a change of soil for the cultivation of the 

 bulbs, as the fields in which the Lilies are grown in Japan 

 are probably saturated with the fungus. He also recom- 

 mends the careful lifting of the bulbs and partial drying or 

 "sweating" before they are packed for exportation. It 

 might be well to dip all the bulbs in a solution of salicylic 

 acid before packing them should there be any suspicion of 

 the presence of the fungus. Another disease has lately 

 attacked L. auratum in English gardens, destroying the 

 strongest stems in a few days, usually when the flowers 

 are about to open. It has been described as a kind of sun- 

 stroke, and it has all the appearance of scalding. 



